Suppose that you want to test the effects of different dishwashing detergents on dishes that have food stuck to them. To test the differences, you wash three loads of the same dishes, each with a different type of detergent, all in warm water. You al?

Dishwashing detergent - independent variable  - changeable type1,2,3 etc

dish washer - fixed variable - constant
dishwasher wash-settings - fixed variable - constant
food stuck on plates - fixed variable - constant
time food dried on plates - fixed variable - constant
type of plate - fixed variable - constant
location of plate/s in dishwasher - fixed variable - constant

Number of testing cycles - experimental variable - needs to be the same for each independent variable.

Observable food left on plate - independent variable ( results)

You will also need to develop a hypothesis - (what you think the result will be)